This application claims the benefit of Korean Patent Application No. 2004-52307, filed on Jul. 6, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to decoding of data, and more particularly, to an apparatus for and a method of pipelining-decoding a coded bitstream, and a computer-readable recording medium for storing a computer program for controlling the apparatus.
2. Description of the Related Art
U.S. Patent Publication No. 20030185298A1 discloses a conventional decoding method, entitled “Method of Operating a Video Decoding System.” In the conventional decoding method, Moving Picture Experts Group (MPEG)-2 decoding is divided into several modules: variable length decoding (VLD), inverse quantization (IQ), inverse discrete cosine transform (IDCT), pixel filtering, and motion compensation (MC), performed using a pipelining method. Unlike the method disclosed in the above mentioned patent publication or other conventional decoding methods, for example, MPEG-1, MPEG-4, H.261, H.263, or the like, H.264/advanced video coding (AVC) includes, in decoding, deblocking filtering as one among post processes, in order to improve picture quality and compression efficiency.
However, where performed using a pipelining method, decoding with deblocking filtering causes trouble. For example, pixel values which have not undergone deblocking filtering are required to execute intra-prediction during MC. However, where deblocking filtering is performed using the pipelining method, deblocking-filtered pixel values are used during intra-prediction. Thus, decoding is not correctly performed. In order to avoid this problem, in the case of H.264/AVC, a deblocking filtering module is performed in the unit of each picture, without using the pipelining method separately from the other modules of the decoding method.
As described above, the conventional decoding method is slowly performed with not using the pipelining method for deblocking filtering. In particular, an increase in the number of slices of a picture causes a more serious problem. In addition, pixel values which have been recovered using the results of intra-prediction are stored in an external memory and then fetched from the external memory to perform deblocking filtering, thereby lowering the practicability of a data bus. As a result, accessing the external memory induces delay, thereby further slowing the decoding.